What is Missouri's winter weather outlook?

By Mike Szydlowski

Tuesday

Nov 20, 2018 at 8:00 AM

Like it or not, the snow has come early this year. What does that mean for this winter? An early snow does not necessarily mean a snow and cold winter. However, an early blast of cold air does offer clues to some of the forces that will be shaping our winter this year. Let’s take a look at what some of the experts are thinking for this year.

Polar Vortex

The polar vortex is expected to be weak this year. That means a warm winter, right? Not really. The polar vortex is the circulation pattern in the north pole. It spins the cold air around the pole. In years with a strong polar vortex, cold air blasts from the north are rarer as the strong circulation holds the cold air near the pole. Years with a weak circulation allow cold to escape more regularly, which gives parts of the United States greater chances for cold weather outbreaks throughout the winter.

The early cold snap this year is one clue that the vortex is willing to allow some cold to escape its circulation. Unless this cold air escape was a big fluke (which is possible), we may expect there to be more regular cold air outbreaks this winter.

11-Year Solar Cycle

The sun goes through an approximately 11-year cycle. The energy during this cycle fluctuates. The fluctuations are not huge as the Sun is still giving the Earth a lot of energy all the time. However, there are certain times during the cycle where the sun is giving the earth just a little less energy. Less energy targeted toward the equator means there is a little less temperature difference between the equator and the poles.

Of course, there is still a huge difference in temperature between the equator and the poles, but during the lower energy sun cycle the difference is just a little less. A smaller temperature difference means that it is easier for cold air to ooze down from the poles. Where are we on the 11-year sun cycle? We are at the low energy portion of the cycle. That is another clue that this winter could be cooler than normal.

The Modoki

The what? You probably have not heard about the Modoki, but you have likely heard of El Nino. The name El Nino described a condition where a huge pool of warm water develops in the Pacific Ocean. This warmer than normal pool of water is able to shift the forces in the atmosphere in predictable ways. El Nino conditions (or the opposite condition called La Nina) are one of the biggest clues to atmospheric patterns each winter.

This year we have a special variation of El Nino called a Modoki. A Modoki is also characterized by a developing warm pool of water in the Pacific Ocean. The difference is that this warm pool of water develops in a different location within the Pacific. The different locations impact the atmosphere in different ways and this pattern often causes the jet stream to form a ridge in the western United States and a trough in the eastern United States.

Think of the jet stream as a giant wave that weaves across the entire globe. This wave separates the warm and cold air. The coldest air will be north of the jet stream while the warmest air will be south of the jet stream. When the Modoki forms a ridge in the western United States, the coldest air will be trapped up in Canada. For this reason, the west has a more likely chance of being warmer than normal. The Modoki causes the jet stream to form a dip, or trough, in the eastern half of the United States. This allows the cold air from Canada to travel much further south.

Winter Conclusion

So what does this all mean for Missouri? The early cold has confirmed the likelihood of a weak polar vortex. Scientists know that we are on the low energy side of the sun’s 11-year cycle. And scientists are currently watching a strengthening Modoki develop. All this together adds to greater chance that Missouri will have a cooler than normal winter.

Of course, these are all just clues and things will fluctuate. The jet stream will move around and that will give us some warm and some cold periods. Patterns will develop and give us changing weather too. Weather systems will form and it’s anybody’s guess on the tracks they will take. The patterns discussed this week just give scientists clues to the likelihood of the average trends. And at this time, these trends point to a little colder than normal…particularly as the Modoki continues to strengthen later in winter. If all this is true, be safe, but be sure to enjoy this magical time of year.

Mike Szydlowski is the science coordinator for Columbia Public Schools.

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